This invention relates to dip cells for the measurement of conductivity of liquid. More particularly, it relates to improved construction of dip cells.
In the measurement of conductivity of a liquid, a conductivity dip cell is commonly used which comprises an electrode surrounded by a non-conductive envelope having a capillary opening therein through which the liquid may pass to come in contact with the electrode. The capillary opening is of a given length thereby providing a resistance path which will vary with the conductivity of the liquid. The remainder of the bath as well as an electrode immersed in the bath, form the opposite electrode of the dip cell because the overall resistivity of the bath is very low compared to the high resistance path through the capillary.
In making such measurements, however, error can be introduced if the gases, foam, or other non-completely liquid materials enter the capillary passageway thus changing the resistance in the passageway. Furthermore, whether the material in the capillary is liquid or some undesirable gaseous-liquid mixture, it is sometimes difficult to remove the material from the capillary to permit a subsequent fresh reading of liquid from the bath.
It is therefore an object of this invention to provide means for inhibiting the entry of such gaseous materials into the capillary tube.
It is a further object of the invention to provide means for purging the capillary passageway of a conductivity dip cell of gas or liquids to permit subsequent entry of fresh liquid into the dip cell for subsequent measurement.